Elucidating the mechanism of immune suppression by sprysec effectors from potato cyst nematodes

Persistent nematode infections are a major threat to important food crops. These round worms manipulate plant cell morphology and physiology to establish sophisticated feeding structures. Remarkably, they are able to escape detection by the plant immune system, despite their size and the damage they cause to the host upon infection. Modifications to plant cells are largely attributed to the activity of nematode secreted effectors. It has been recently shown that members of the SPRYSEC effector family from potato cyst nematodes selectively supress host cell death and disease resistance mediated by plant immune receptors. We aim to unravel the, as of yet, unknown molecular mechanism behind immune suppression by these effectors. Evidence supports a model where SPRYSECs function as specificity modifiers of host ubiquitin complexes for nematode-induced proteasomal degradation of host immune receptors. Experiments with protein-protein interaction methods, directed mutagenesis and protein ubiquitination assays among other techniques, will enable us to substantiate our model. If indeed the diverse SPRYSEC effector family functions as versatile suppressors of immunity, the expansion of this family may reflect adaptations to diversification of plant immune receptors. Therefore our results may provide insight into the basis for virulence of nematodes in plants.